Along with continuous evolution of wireless communication technologies and standards, mobile packet services are greatly developed, and a data throughput capacity of single User Equipment (UE) is continuously improved. For example, for a Long Term Evolution (LTE) system, data transmission at a maximum downlink rate of 100 Mbps may be supported within a 20 M bandwidth, and in a subsequent LTE Advanced system, the data transmission rate may further be increased and may reach up to 1 Gbps.
Expansive increase of data traffic of UE makes existing network resources gradually starved, particularly under the condition that it is impossible to widely distribute a network for a new-generation communication technology (for example, 3rd-Generation (3G) and LTE), followed by an incapability in meeting rate and traffic requirements of users and worsening of user experiences. How to prevent and change such a condition is a problem an operating company must consider. On one hand, popularization and network deployment of new technologies are required to be accelerated; and on the other hand, existing networks and technologies are expected to be enhanced to achieve a purpose of rapidly improving network performance. It is well known that a Wireless Local Area Network (WLAN) which has been widely applied at present, particularly an Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard-based WLAN, besides a wireless network technology provided by the 3rd Generation Partnership Project (3GPP), has been widely applied to hotspot access coverage in families, enterprises and even the Internet, wherein a technical specification proposed by the Wireless Fidelity (Wi-Fi) Alliance is applied most widely, so that a Wi-Fi network is usually equivalent to the IEEE 802.11 standard-based WLAN in practice. A Wi-Fi module is also adopted to describe a WLAN supporting wireless transceiver and processing module in a network node hereinafter without confusions.
On such a premise, some operating companies and corporations have proposed to fuse a WLAN and an existing 3GPP network to implement joint transmission to achieve purposes of offloading and network performance improvement. The 3GPP Service and System Aspects 2 (SA2) approves an Access Network Discovery and Selection Functions (ANDSF) solution, and provides a mode of selecting a target access network for UE according to a strategy of an operating company.
A communication protocol 3GPP Release 10 (R10) defines an ANDSF standard, and an ANDSF implements intelligent network selection as an access anchor, implements effective offloading of network access through interactive cooperation of networks and UE, and is consistent with an operation direction of cooperation of multiple networks in the future. The ANDSF formulates a strategy based on information such as a network load, a capability of the UE and user subscription information, helps a user of the UE to select an optimal network system for access and implements cooperative operation of multiple access manners. The ANDSF may be deployed independently, and may also be arranged together with another network element. At present, a mainstream view of the industry is that the ANDSF may be deployed on Program-Controlled Computer (PCC) equipment.
An ANDSF is a core-network-based WLAN interworking solution, and does not consider influence on an access network. In addition, since the ANDSF is a relatively static solution, and may not be well adapted to a condition that a network load and channel quality dynamically change, a WLAN interworking discussion on a 3GPP access network group is also conducted. During WLAN and 3GPP wireless interoperation in 3GPP Release 12 (R12), a WLAN offloading execution rule and a triggering mechanism are introduced.
However, a core network mechanism and an auxiliary information mechanism from a Radio Access Network (RAN) may not provide load and channel conditions for a network side to use in real time for combined use of radio resources. In addition, data from the same bearer may not serve on both 3GPP and WLAN links. Therefore, a requirement on integration of a WLAN and a 3GPP network is remade in the 65th RAN plenary meeting.
Compared with a strategy and triggering-based WLAN offloading solution which has been researched at present, RAN layer aggregation-based WLAN and 3GPP network integration, called as WLAN and 3GPP network tight coupling for short, is similar to carrier aggregation and dual connectivity, and provides better control and utilization of resources on dual connectivity for an overall system. Tight integration and aggregation in a radio layer allows more real-time joint scheduling of radio resources of a WLAN and a 3GPP network, thereby improving Quality of Service (QoS) for a user and an overall system capacity. By better managing radio resources between users, an overall throughput of all the users may be improved, and the overall system capacity may be improved. Based on a real-time channel condition and a system service condition, each link scheduling decision may be made to a layer of each packet. A user plane is anchored in a reliable LTE network, and performance may be improved by rollback to the LTE network.
WLAN and 3GPP network tight coupling may be applied to a co-located scenario (an eNB and a wireless AP complete a RAN-layer integration operation through an internal interface) and a non-co-located scenario (the eNB and the AP complete the RAN-layer integration operation through an external interface), which are substantially similar to 3GPP carrier aggregation and dual connectivity respectively.
In a WLAN and 3GPP network tight coupling application scenario, APs may be divided into multiple AP groups. Movement of UE in the same AP group may not be notified to a 3GPP network, and namely, may be transparent to a network element of an LTE network. However, movement of the UE in different AP groups may require a network element of the 3GPP network to participate in control to better balance a load and improve transmission efficiency or quality of a system capacity.
There is now introduced a new problem of how to transmit AP group information to UE to enable the UE to better implement handover in the AP group, thus implementing tight coupling between an LTE network and a WLAN.